This invention relates to a composition for cleaning contact lenses which comprises a silicone surface active agent having cleaning activity for contact lens deposit.
The tendency of contact lens materials to form deposits necessitates regular cleaning of the contact lenses. Deposits from the tear film include protein, lipid and mucin, and deposits from external sources include cosmetic deposits, such as from mascara or hair spray, or materials deposited when the lens is handled.
Surfactant contact lens cleaners, which employ a surface active agent having cleaning action, are used to remove lipid deposits, loosely bound protein deposits, and other deposits. Surfactant cleaners are used for hard and soft contact lenses. Hard lenses include polymethylmethacrylate lenses and rigid gas permeable (RGP) lenses formed of a silicon acrylate type or a fluorosilicon acrylate type polymer. Soft lenses include hydrophilic hydrogel lenses. Surfactant cleaners are generally used in conjunction with finger rubbing or other mechanical cleaning, followed by rinsing to remove the deposits.
A wide variety of surface active agents are known for use as a primary cleaning agent in contact lens cleaning compositions, including various anionic, cationic, nonionic or amphoteric surface active agents, and certain combinations thereof.
U.S. Pat. Nos. 4,048,122 and 4,126,587 (Sibley et al.) describe compositions for cleaning soft and silicone contact Lenses which contain a polyoxyalkylene modified silicone resin and at least one fatty acid amide or nitrogen analog thereof. Additionally, compositions for cleaning machined lens blanks are described which do not employ any silicone resin and include a combination of the amides or nitrogen analogs as the primary cleaning agent. The described silicone resins are preferably block copolymers having the formula: EQU TSi(O(SiMe.sub.2 O).sub.x (C.sub.n H.sub.2n O).sub.y T'.sub.3
wherein T is alkyl of from 1 to 3 carbon atoms, usually methyl, T' is alkyl of from 1 to 6 carbon atoms, usually 3 to 4 carbon atoms, n is an integer of from 2 to 30, and x and y are numbers within various ranges.
U.S. Pat. No. 4,613,380 (Chen) reports tests evaluating the effectiveness of various agents for removing lipid deposits from silicone elastomer contact lenses. A silicone glycol copolymer (Dow Corning.RTM. 190, a silicone polymer containing polyoxyethylene and/or polyoxypropylene side chains), designated in the patent as "Surfactant 1", was employed as a comparative example in tests for effectiveness at removing lipid deposits from the contact lenses.
It will be appreciated that the silicone resin in the Chen patent was reported as not particularly effective as a primary cleaning agent for contact lens deposits. Additionally, the compositions described in the Sibley et al. patents which include the described silicone resin require the inclusion of the amide surfactant as a primary cleaning agent.